1. Field of the Invention
The present invention relates to a technology of recording, position of focus measuring point, with image data, on to the storage medium in such as digital cameras.
2. Description of the Related Art
Many conventional cameras with ability to verify goodness/badness of object image on the spot have been proposed. However, due to space and cost restrictions, display unit such as LCD (liquid crystal display) monitor used in these cameras are limited in size. Thus, it has been quite difficult to verify goodness/badness of the object image using such display units. In addition, even though the sensed image on display unit can be zoomed to evaluate focus condition of the object image, the position of focus measuring point was unknown.
Japanese Patent Laid-Open No: 2000-125178 has proposed a method to solve this problem by displaying superposition of the object image and focus detection point of the image for confirmation before recording it to the storage medium.
Moreover, in Japanese patent laid-open No: 2002-044493 a image capturing apparatus has been proposed, wherein information of focus detection position obtained by focus controlling unit is saved with image data, into storage. And, in Japanese patent laid-open No: 2002-044493 has proposed a way to readout location detection data with image data from storage medium and display location detection data overlapped with image data. In addition, it has made possible to zoom in the neighborhood of focus detecting point.
However in focus-lock shooting procedure, first the main object is focused using focus control unit and then the photo composting is changed by moving the focus point away from the main object while keeping the focus point distance memorized. When focus-lock shooting procedure is used, the composition of photo is changed after focusing. There will be cases where actually focused main object might not recorded as focus measuring point in the conventional technologies given above which used for recording the position of focus detection point with the image data. Here, we explain focus-lock shooting procedure using FIGS. 11A to 11C. In FIGS. 11A to 11C there are 19 focus detecting points, focus control unit can control focus utilizing each focus detection point. Each focus detection point is named from [A]-[S] to make explanation more convenience. Even though focus control unit can control each focus detection point [A]-[S] independently, focus control precision depends on the focus detection point. Thus, focus detection unit with multiple focus detection points might prefer to use the highest precision detection point (As in example: the center focus detection point).
In focus-lock shooting procedure, first the main object, which is the human, is captured with the center focus-detection-point [J] as a temporary composition (FIG. 11A) by adjusting the focus on to the main object and then focus locking, by utilizing the focus control unit. Then, the image capturing apparatus is panned (FIG. 11B) to the desired object. In the new image composition after alteration, initially focused human has moved near to the focus detecting point [F].
Even though the main object is located near distance measurement point F, distance measurement point used by the focus control unit for focusing is J. Thus, the recorded distance measurement point with image data is distance measurement point J, and it has been displayed as the distance measurement point on the image (FIG. 11C). Therefore, when focus condition is checked, the position in which the focus was actually adjusted becomes uncertain. Moreover, a position, which has not been focused after frame alternation, will be zoomed.